I use topographic maps from MyTopo.com with UTM grids and Lat/Long tics printed on them.

I know the difference between true north (TN) and magnetic north (MN) shown on the maps. For me living in the United States I tend to imagine true north being somewhere north of the Mississippi River.

Via email communication with the folks at MyTopo.com I have confirmation that on my maps the grid north (GN) is based upon the UTM grid at the center of the map.

Now, I have two questions about true north references on topo maps. The answer might be specific to how MyTopo maps are printed - I'm not sure.

Question #1: Do longitude lines (north-south) always lie on true north? Or might they be slightly off? Maybe something to do the datum model?? These are hard to work with on my maps since I only have longitude tics printed, but I'd still like to know.

Question #2: Are the left and right edges of the MyTopo maps always true north? I think these have the highest chance of being true north, but I'm not 100% sure of that. I'm waiting - hoping - to hear back from MyTopo on this question.

I've seen some people recommend orienting the map to true north using the TN symbol lines, but they are kind of short for easy use.